The present invention relates to a method for controlling a continuously variable transmission, and particularly to a method of controlling a desired engine speed of an engine equipped with a continuously variable transmission.
In a vehicle equipped with a continuously variable transmission, it is proposed a continuously variable transmission such that a desired engine speed at a steady state is determined to be a function of a throttle opening in order to obtain a minimum fuel consumption at a steady state. A horsepower of an engine is determined to be a function of a throttle opening. In such an engine equipped with the continuously variable transmission, the engine speed varies in a large scale when the throttle opening varies a little at a low vehicle speed. For example, when the throttle opening varies by the amount of few percentages, the engine speed happens to cause the variation of the engine speed up to 1000 r.p.m. Such a wide variation of the engine speed impairs the drivability. As the desired engine speed is designed to obtain the minimum fuel consumption regardless of the vehicle speed, the vehicle speed does not promptly increase even when an accelerator pedal is moved up to a big stroke at a high vehicle speed. In this condition, the vehicle speed slowly increases in order to obtain the minimum fuel consumption. This results in the bad drivability.